From 0bf72833307bf500ebec1a08641600f12cda0434 Mon Sep 17 00:00:00 2001
From: Jakub Konka <kubkon@jakubkonka.com>
Date: Wed, 13 Apr 2022 16:22:24 +0200
Subject: [PATCH] dwarf: gen debug info for arrays

---
 src/codegen.zig    |  2 --
 src/link/Dwarf.zig | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/codegen.zig b/src/codegen.zig
index 2ace45c8cb..68e1f3697f 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -203,7 +203,6 @@ pub fn generateSymbol(
         },
         .Array => switch (typed_value.val.tag()) {
             .bytes => {
-                // TODO populate .debug_info for the array
                 const payload = typed_value.val.castTag(.bytes).?;
                 const len = @intCast(usize, typed_value.ty.arrayLenIncludingSentinel());
                 // The bytes payload already includes the sentinel, if any
@@ -212,7 +211,6 @@ pub fn generateSymbol(
                 return Result{ .appended = {} };
             },
             .aggregate => {
-                // TODO populate .debug_info for the array
                 const elem_vals = typed_value.val.castTag(.aggregate).?.data;
                 const elem_ty = typed_value.ty.elemType();
                 const len = @intCast(usize, typed_value.ty.arrayLenIncludingSentinel());
diff --git a/src/link/Dwarf.zig b/src/link/Dwarf.zig
index fc392bfe3e..bd7f429177 100644
--- a/src/link/Dwarf.zig
+++ b/src/link/Dwarf.zig
@@ -270,6 +270,27 @@ pub const DeclState = struct {
                     try self.addTypeReloc(atom, ty.childType(), @intCast(u32, index), null);
                 }
             },
+            .Array => {
+                // DW.AT.array_type
+                try dbg_info_buffer.append(@enumToInt(AbbrevKind.array_type));
+                // DW.AT.name, DW.FORM.string
+                try dbg_info_buffer.writer().print("{}\x00", .{ty.fmt(target)});
+                // DW.AT.type, DW.FORM.ref4
+                var index = dbg_info_buffer.items.len;
+                try dbg_info_buffer.resize(index + 4);
+                try self.addTypeReloc(atom, ty.childType(), @intCast(u32, index), null);
+                // DW.AT.subrange_type
+                try dbg_info_buffer.append(@enumToInt(AbbrevKind.array_dim));
+                // DW.AT.type, DW.FORM.ref4
+                index = dbg_info_buffer.items.len;
+                try dbg_info_buffer.resize(index + 4);
+                try self.addTypeReloc(atom, Type.usize, @intCast(u32, index), null);
+                // DW.AT.count, DW.FORM.udata
+                const len = ty.arrayLenIncludingSentinel();
+                try leb128.writeULEB128(dbg_info_buffer.writer(), len);
+                // DW.AT.array_type delimit children
+                try dbg_info_buffer.append(0);
+            },
             .Struct => blk: {
                 // DW.AT.structure_type
                 try dbg_info_buffer.append(@enumToInt(AbbrevKind.struct_type));
@@ -564,6 +585,8 @@ pub const AbbrevKind = enum(u8) {
     pad1,
     parameter,
     variable,
+    array_type,
+    array_dim,
 };
 
 /// The reloc offset for the virtual address of a function in its Line Number Program.
@@ -1357,6 +1380,18 @@ pub fn writeDbgAbbrev(self: *Dwarf, file: *File) !void {
         DW.AT.name,      DW.FORM.string,
         0,
         0, // table sentinel
+        @enumToInt(AbbrevKind.array_type),
+        DW.TAG.array_type, DW.CHILDREN.yes, // header
+        DW.AT.name,        DW.FORM.string,
+        DW.AT.type,        DW.FORM.ref4,
+        0,
+        0, // table sentinel
+        @enumToInt(AbbrevKind.array_dim),
+        DW.TAG.subrange_type, DW.CHILDREN.no, // header
+        DW.AT.type,           DW.FORM.ref4,
+        DW.AT.count,          DW.FORM.udata,
+        0,
+        0, // table sentinel
         0,
         0,
         0, // section sentinel